e., minimized their anticipated guilt) to

trials in which they returned less than they believed their partner expected (i.e., enhanced their financial reward). The duration of the decision phase was modeled as the time to decision. There was no significant difference in the response time between trials in which participants matched expectations (mean = 3412.29 ms, sd = 1310.65) as compared to trials in which they returned less than their expectation (mean = 3666.87 ms, sd = 1475.47; b = 0.25, se = 0.14, t = 1.80, p = 0.08). It is important to note that this response XAV-939 solubility dmso time is not particularly meaningful as participants were required to scroll through their choices and the starting point was random (see Experimental Procedures). The contrast, illustrated in Figure 4, revealed increased activity in the insula, supplementary motor area (SMA), dorsal

anterior cingulate (DACC), dorsolateral prefrontal cortex (DLPFC), and parietal areas, including the temporal parietal junction (TPJ), when participants matched their second-order beliefs about their partner’s expectations, thus minimizing guilt. Returning less than their second-order belief, and thereby increasing financial gain, was associated with greater activity in the ventromedial prefrontal cortex VMPFC, bilateral nucleus accumbens (NAcc), and dorsomedial prefrontal cortex (DMFPC) (See Table S2 for all identified regions). While the main contrast illustrates regions associated with minimizing expected guilt as compared to maximizing financial payoff, an Selleck Obeticholic Acid additional question of interest is whether these activations change parametrically as a function of the actual deviation from matching expectations. To address this question we tested a parametric contrast that compared trials in which participants matched expectations to linear deviations from MTMR9 expectations (in 10% increments). Similar to the main contrast, matching expectations

was associated with increased activity in the right insula, right DLPFC, SMA, ACC, and precuneous (see Figure 5 and Table S3). Returning incrementally less than expectations was associated with increased activity in the bilateral NAcc and MPFC (including VMPFC, DMPFC, and ACC). However, participants systematically made slightly less money in trials in which they matched expectations (mean = $12.28, sd = 5.88) compared to trials in which they returned less than they believed the other player expected ($14.58, sd = 6.79; beta = −2.08, t = 2.53, p < 0.05). To address this potential confound and to rule out the possibility that the insula is simply tracking forgone financial payoffs rather than guilt aversion, we ran an additional analysis (see Supplemental Information) that allowed us to examine the effect of matching expectations while controlling for the amount of money that subjects return (i.e., their forgone financial payoff).